1. Field of the Invention
The invention relates to the detection of an object covering the surface of a keyboard.
2. Related Art
Self-operating apparatuses have, as a rule, a keyboard on which the user inputs confidential or secret data, especially a secret number designated as PIN (personal identification number). In order to access these and similar data illegally, a keyboard can be manipulated by superposed similar keyboards or other objects. An arrangement which discovers such manipulations must, however, simultaneously be unobtrusive, sturdy, and be secured against wanton damage (vandalism).
It is the problem of the invention, therefore, to give a corresponding arrangement.